Music sequencers are well-known devices which generate musical accompaniment for a performer. Such devices often include pre-programmed musical sequences which are generated by the sequencer in response to various control switches or the like on the device itself. Other, more sophisticated, sequencers include such a capability but are also capable of receiving control signals from other musical instruments and/or controller devices to produce selected musical accompaniment.
As indicated above, many music sequencers operate with MIDI control signals. The MIDI signals are generated and used in accordance with a known set of format specifications. If a particular music sequencer is capable of operating with MIDI signals, that sequencer can communicate and operate with other MIDI devices from other manufacturers.
Some music sequencers, in response to musical notes in MIDI format generated by a musical instrument, are capable of recognizing certain combinations of such notes as musical chords, and in addition to actually producing the notes, are further capable of producing musical patterns based upon those chords as accompanying music. In operation, such sequencers search for particular three or four note combinations which comprise a musical chord, in the stream of notes provided to it by the musical instrument. In such a case, the sequencer will adjust the notes of the musical pattern it produces to harmonize with the musical notes provided by the musical instrument. The adjustment is accomplished quite rapidly, so that it appears that the change in the accompaniment occurs simultaneously with the playing of the musical notes by the performer on the musical instrument.
Keyboard instruments are frequently used for the above-described musical notes, because they are widely used by performers and also because a keyboard can typically be readily adapted to produce the required MIDI signals. One such instrument is the accordion. Other instruments, including a guitar, could be used. In a typical arrangement, an accordion will use three MIDI channels (1, 2 and 4 herein) to communicate with the music sequencer, with channel one being for the musical notes from the right-hand keyboard of the accordion, channel two for notes from the left-hand bass buttons, and channel four for the left-hand chord buttons. In typical operation, the melody of the musical piece will be played on the right-hand keys of the accordion while the bass and the chord portions of the music will be played with the left hand on the left side bass and chord buttons.
On the accordion, the chord buttons on the left-hand side of the instrument are well suited for producing the control signals necessary for a music sequencer, since operation of each chord button will produce a corresponding three-note chord in conventional MIDI format. However, with typical accordion musical pieces, the chord buttons are normally played after the start of a music measure. For accompaniment, the sequencer requires the MIDI signals to be present at the beginning of a musical measure, which is the normal time for a chord change. Thus, normal use of the chord buttons on an accordion will not be in proper time for the generation of desired chords by the music sequencer at the start of a music measure. There have been attempts to remedy this by playing the accordion chord buttons at the beginning of a music measure or by using foot pedals to produce the desired MIDI signals at the beginning of the measure; however, such techniques have proven to be both difficult to master for a performer and often produce less than desirable results.
It would be hence desirable to have a system which uses conventional keys, buttons or other features of a musical instrument in such a way that the required MIDI control signals are produced for the generation of chord accompaniment (or chord changes) by the music sequencer at the start of a music measure.